The present invention relates to hearing devices for aiding the hearing impaired and the profoundly deaf, and more particularly to an In The Ear (ITE) auxiliary microphone connected to a Behind The Ear (BTE) speech processor through a removable ear hook. The microphone of the present invention is especially useful for a user conversing over a telephone.
Implantable Cochlear Stimulation (ICS) systems are known in the art. Such systems are used to help the profoundly deaf (those whose middle and/or outer ear is dysfunctional, but whose auditory nerve remains intact) to hear. The sensation of hearing is achieved by directly exciting the auditory nerve with controlled impulses of electrical current, which impulses are generated as a function of perceived audio sounds. The audio sounds are picked up by a microphone carried externally (not implanted) by the deaf person and converted to electrical signals. The electrical signals, in turn, are processed and conditioned by a Wearable Signal Receiver and Processor (WP) in an appropriate manner, e.g., converted to a sequence of pulses of varying width and/or amplitude, and then transmitted to an implanted receiver circuit of the ICS system. The implanted receiver circuit generates electrical current as a function of the processed signal it receives from the WP (which in turn is based on the audio sounds picked up by the external microphone). The implanted receiver circuit is connected to an implantable electrode array that has been implanted into the cochlea of the inner ear. The electrical current generated by the implanted receiver circuit is applied to individual electrode pairs of the electrode array. It is this electrical current which directly stimulates the auditory nerve and provides the user with the sensation of hearing.
While known ICS systems have succeeded in providing hearing to the deaf, ICS systems also have the disadvantage of appearing unsightly. ICS systems include an external headpiece positioned on the side of the user""s head, and require an external cable running from the external headpiece to the WP. The WP is typically worn or carried by the user on a belt or in a pocket. While the WP is not too large, it is likewise not extremely small, and hence also represents an inconvenience for the user. The cable which connects the WP with the headpiece is particularly a source of irritation and self-consciousness for the user.
The above-described aesthetic considerations and inconvenience of an external wire are addressed by U.S. Pat. No. 5,824,022, issued Oct. 20, 1998, for xe2x80x9cCochlear Stimulation System Employing Behind-The-Ear (BTE) Speech Processor With Remote Control.xe2x80x9d The ""022 patent teaches a small single external device that performs the functions of both the WP and the headpiece. The external device is positioned behind the ear to minimize its visibility, and requires no cabling to additional components. The ""022 patent is incorporated herein by reference.
While the BTE device taught by the ""022 patent resolves the issues of aesthetics and inconvenience, the placement of the microphone in the BTE device case results in poor microphone performance when using a telephone. The near field acoustic characteristics of known telephones, and the absence of a seal between the telephone earpiece and the microphone in the BTE case, degrades the coupling of low frequency information up to about 1 KHz. Further, known ICS systems and hearing aids use a telecoil residing near the earpiece of a telephone handset to detect the magnetic field produced by the speaker in the handset, however, low magnetic field phones and cell phones using piezo transducers, do not couple well with telecoils.
Therefore, there is a need to improve the performance of known ICS systems when the user is conversing over a telephone.
The present invention addresses the above and other needs by providing an In The Ear (ITE) microphone that improves the acoustic response of a Behind The Ear (BTE) Implantable Cochlear Stimulation (ICS) system during telephone use. An acoustic seal provided by holding a telephone earpiece against the outer ear provides improved coupling of low frequency (up to about 1 KHz) sound waves, sufficient to overcome losses due to the near field acoustic characteristics resulting from the telephone microphone cooperation. In a preferred embodiment, the ITE microphone is connected to a removable ear hook of the BTE ICS system by a short bendable stalk.
In accordance with one aspect of the invention, there is provided an ITE microphone for a BTE ICS system, which microphone is placed within the concha of the ear. When a telephone handset is held against the ear, the phone seals against the outer ear, creating a chamber wherein the microphone resides. Sealing the microphone within such chamber results in improved frequency fidelity due to the sealing in of the sound pressure. Such sealing also reduces the amount of outside noise that reaches the microphone. Advantageously, the BTE ICS system does not require any earmolding to provide adequate sealing. Further, the positioning of the microphone within the ear improves hearing by using the natural acoustics of the ear.
It is a further feature of the invention to provide a BTE ICS system that works equally well with low magnetic field phones and cell phones using piezo transducers which do not couple well to a telecoil. The ITE microphone relies entirely on the acoustic signal transmitted by the speaker in the telephone handset, which speaker is designed to achieve the acoustic performance objectives of the unaided hearing population. The performance of the BTE ICS system using the ITE microphone is therefore unaffected by the type of speaker (or sound transducer) used in the telephone handset.
It is an additional feature of the present invention, that when exercised in conjunction with an ICS system, there is no acoustic feedback from a microphone to affect performance. Conventional hearing aids use a speaker in the user""s ear to broadcast an amplified acoustic signal to the user. If an ITE microphone was used in the same ear, the result would be severe acoustic feedback. The present invention is applied to ICS systems, wherein the output of the ICS system is electrical stimulation of the cochlea, not an acoustic signal.
It is a further additional feature that use of the ITE microphone does not result in chafing to the skin of the ear. The ITE microphone of the present invention includes a bendable stalk, which stalk retains a shape once the stalk is bent into that shape. The stalk may thus be bent to avoid rubbing against the skin of the ear, and the resulting chafing of the skin.